High electron mobility transistor and manufacturing method thereof

HEMT (1; 21; 31; 51) including a buffer layer (4), a hole-supply layer (6) on the buffer layer (4), a heterostructure (7) on the hole-supply layer (6), and a source electrode (16). The hole-supply layer (6) is made of P-type doped semiconductor material, the buffer layer (4) is doped with carbon, and the source electrode (16) is in direct electrical contact with the hole-supply layer (6), such that the hole-supply layer (6) can be biased to facilitate the transport of holes from the hole-supply layer (6) to the buffer layer (4).